Mask set for multiple exposures in moving-picture cameras and process of making the same



Feb. 9 1926. 1,572,315

SCHOLL MASK SET FOR MULTIPLE EXPOSURES IN MOVING PICTURE CAMERAS ANDPROCESS OF MAKING THE SAME Filed Feb. 21 1923 lllllmllllmll I NashPatented Feb. 9, 1 926.

UNITED STATES 1,572,315 PATENT OFFICE.

nnwann sononn, or NEW roux, n. 1., assrenon so u; w. cams-rm,mcoarename, or new xoax; 1:. an, a conrom'rron or MARYLAND.

MASK SET FOR MULTIPLE EXPOSUBEB IN MOVING-FICTURE CAMERAS AND PROCESS OFMAKING THE SAME.

Application filed February 21, 1828. Serial No. 820,482.

To all whom it may concern:

Be it known that I, EDWARD SoHoLL, citizen of the United States, and .aresident of the city, county, and State of New York, have invented a newand useful Improvement in Mask Sets fonMultiple Exposures inMoving-Picture Cameras and Processes of Making the Same, of which thefollowing is a specification.

When making multiple exposures it is often necessary to protect a partof a film from li ht and light efiects while exposing a neigh oring partand at a later exposure the neighboring part ma be covered and protectedand the origina ly protected part exposed, and if necessary, thisprotecting and exposing may be carried on indefinitely. For example,thirteen exposures may be had of one film, a art being covered each timeso that when a l exposures are complete, the entire film has beenexposed. The coverin of the parts of the film which is not expose mustbe very accurate because of the great magnification when a positive ismade and used in the ordinary manner.

. The object of my invention is to provide a suitable mask or set ofmasks which must be utilized with the greatest accuracy so that themultiple exposures may be had and yet when the film is complete it willappear that there has been only one exposure. This and other objects areaccomplished by my invention, one embodiment of which is hereinaftermore particularly set forth.

For a more detailed description of my invention, reference is to be hadto the accompanyin' drawings, forming a part hereof, in whic Figure 1shows a mask made according to my invention, and

Figure 2 shows a second mask which is also made accordin to my inventionand complementary to it e mask shown in Figare 1.

Figure 3 is a diagrammatic view which illustrates the characteristics ofmy improved mask.

Throughout the various views of the drawings, similar referencecharacters designate similar parts.

Referring to Figure 3, it appears that an object 1 is before a camera ofthe moving picture type and that an ima e is caught by the lens 2 ofthis camera an in due course,

in the absence of any interruption, would be projected on a film 3 inthe conventional manner andthat one exposure would cover an areacorrespondin to the distance between the points 4 an 5. Let it also beassumed that a sensitized metal plate 6 is placed lmmediately in frontof the film 3 and as close thereto as possible without interfering withthe film and an exposure had so that the image is caught on the plate 6and not on the film 3. This plate 6 is then removed and developed, andlet it be assumed that after development, the picture on this plate 6will have two parts 7 and one part 8, it being understood that threeparts are selected for the purposes of illustration and that any numberof parts may be on this 'plate, as desired. Let it be further assumedthat the parts 7 are bounded by the lines 9, 10 and 11 and the lines 9,13, 12 and 11 and the part 8 by the'lines 11, 9 and 13 and that theplate in Figure 1, which may be designate 6, is to have the part marked8 removed and the late in Figure 2, which may be designated 6", willhave the part marked 7 removed so that the plate 6 will be thecomplement of the plate 6. Then an etchers needle is applied; to thelines 11, 12 and 13 in the late 6 and to the lines 9, 10 and 11 in the pate 6 and a cut is made clear to the body of the plate. Except for theselines which are exposed, all other parts of the plate are protected andthe plate is then immersed in acid which eats away the metal at theexposed lines and thereby makes the part 8 so that it is removed readilyfrom the plate 6 and the part 7 so that it is removed readily from theplate 6". These plates are then complementary one to the other and anexposure may then be had with these plates or masks, as indicated inFigure 3, the first exposure being had, let us say, with the plate 6 sothat, the exposure is entirely through .the opening 8 and after that ishad, the film 3 is reversed and put into its original position and thenthe mask 6 is removed and the mask 6 substituted and thereafter thesecond exposure will be through the opening 7 so that the film isentirely protected and accurately protected during each exposure, exceptas to the parts where an exposure is desired and absolute accuracy isassured because of the manner in which each mask ismade. Obviously, by

' of the camera.

increasing the number of removable parts 7 effect of a complete filmmade with one of and 8 and the number of masks to correspond, it ispossible to make an indefinite number of exposures to correspond.

The material of which each mask is made is a matter of selectionaccording to results desired. If possible, a metal such as zinc, brass,silver or copper should be used, but where this is not possible, glassmay be employed and some acid is then used which will attack only theunprotected parts and all parts are protected, except what is to beremoved. The advantage of using glass is that a protected part may beleft which is entirely surrounded by removed material, and thedisadvantage is that glass is brittle and apt to break because of thejarring mechanical movements incidental to the mechanism Because of thisdanger of breaking, I prefer to use metal plates Wherever such can beemployed.

It will be noted that if an exposure were had on the film 3 and thiswere transferred to a plate, as has been done before in making suchmasks, the picture so transferred would be a little too large and thereducing of it would be a matter of judgment which is almost sure toresult in mistakes as no one can be perfectly accurate in judging whereto reduce. Bythe use of my invention, no judgment is required at allbecause the plate is exposed in the exact position where it is to beused so that great accuracy is assured. Of course, this plate is veryslightly out of focus, but the error is so slight that it is found to beimmaterial and not noticeable in practice.

By the use of my invention, it has been possible to photograph actorswith one or more exposures and a model of a building, such as theBastile with one or more exposures and yet when the film is complete theactors will appear not before a model, but before a full sized structurewhich gives the full sized objects beside life sized actors.

\Vhile I have shown and described one embodiment of my invention, itisobvious that it is notrestricted thereto, but that it is broad enoughto cover all structures that come within the scope of the annexedclaims.

Having thus described my invention, what I claim is: g

1. process of making a plate of a mask set for multiple exposures in amoving picture camera which consists in exposing a sensitized plate sothat an image is thrown directly upon it in the place where the mask isto be used and then developing the plate, outlining with an etchingneedle the form desired, protecting other parts of the plate and thenpermitting the etched lines to be eaten by an acid or similar means,whereby a mask is formed.

2. The process of making a plate of a mask set for multiple exposureswhich consists in sensitizing a plate and then exposing it in a movingpicture camera in the position where it is to be used, then developingthe same, and then removing by etching the part or parts of the platethrough which a film is to be exposed.

3. A mask for moving picture cameras which is composed of a plate withparts removed accordlng to an exposure of the plate had in the positionin which the plate is to be used and while the plate was in a light,sensitive condition.

4. A mask for movin picture cameras which is composed of ap ate withparts removed by etching according to an exposure of the plate, had inthe position in which the plate is to be used and while the plate was ina light, sensitive condition.

In testimony whereof, I have hereunto set my hand.

EDWARD SCHOLL.

